【摘要】 氮气-低矿化度水交替驱是将气-水交替驱中的水段塞替换为低矿化度水段塞。通过试验研究氮气-低矿化度水交替驱驱油特征和提高采收率的机制。结果表明：氮气-低矿化度水交替驱过程中，气体可以进入水难以波及的细小含油孔道，低矿化度水可以增强地层岩石水润湿，促进岩石壁面原油剥离，同时抑制氮气窜流，提高驱替压差，有效提高波及体积和驱油效率；随着渗透率降低，驱替达到稳定状态需要注入的流体体积逐渐增加，提高采收率幅度减小；非均质条件下氮气-低矿化度水交替驱可以有效降低高渗岩心窜流，扩大波及范围；在渗透率级差2～12.3范围内，其采收率较氮气驱提高2.05%～8.08%,较低矿化度水驱提高1.92%～3.97%;随着渗透级差的增大，氮气-低矿化度水交替驱的流动调控能力减弱。更多还原

【Abstract】 N₂/low-salinity water alternating injection is to replace the water slug in gas-water alternate flooding with a low-salinity water slug. In this paper, the characteristics of N₂/low-salinity water alternating injection and its mechanisms for enhanced oil recovery were investigated experimentally. The results show that N₂/low-salinity water alternating flooding has both the advantages of low-salinity water enhancing the water wetting of formation rocks and the inhibition of water slug on N₂ channeling, which can promote the stripping of crude oil and effectively improve the displacement pressure difference. The injected N₂gas can enter the small oil-bearing pores that are difficult to be swept by water, increasing the sweeping volume and oil displacement efficiency. As the effective permeability decreases, the volume of fluid injected to achieve a stable state increases, and the enhanced oil recovery amplitude decreases. Under heterogeneous conditions, N₂/low-salinity water alternating flooding can control the channeling of high permeability layers and expand sweeping area. In the range of permeability level difference 2-12.3, the recovery efficiency of the N₂/low-salinity water alternating injection increases by 2.05%-8.08% compared with N₂ injection alone, and 1.92%-3.97% compared with low-salinity water injection. With the increase of permeability level difference, the flow regulation ability of the N₂/low-salinity water alternating flooding is weakened.更多还原